Thesis(M.S.)--Auburn University, 2006. / Abstract. Includes bibliographic references (p.69-73).

Les propriétés structurales de quatre types de cellulose cristalline (Iα, Iβ, II et IIII), incluant détails structuraux du coeur cristallin et des surfaces, comportement thermique, propriétés mécaniques et inter-conversions allomorphiques, ont été étudiées par des simulations de dynamique moléculaire (MD). Alors que la dynamique moléculaire est supposée reproduire correctement le monde réel, je me suis rendu compte que les paramètres des mailles cristallines élémentaires ainsi que la transition de phase induite par la température ne sont pas reproduites avec une précision satisfaisante. Dans l'objectif de rendre la modélisation plus fiable à compléter les expériences, j'ai dans un premier temps identifié les origines du désaccord et dans un second temps proposé de meilleurs paramètres pour les champs de forces. En utilisant ces paramètres, les caractéristiques structurales des quatre allomorphes de la cellulose sont bien mieux reproduites. Finalement, j'ai utilisé ces paramètres optimisés afin de modéliser d'une façon plus fiable certaines propriétés des cristaux de cellulose : incluant propriétés de surface, liaisons hydrogènes et caractéristiques mécaniques clefs. / The structural and physical properties of four types of crystalline cellulose (Iα, Iβ, II and IIII), including the structural details of the bulk and at the surfaces, thermal behavior, mechanical properties as well as the allomorph conversion, were studied by molecular dynamics (MD) simulation. Although simulations are in principle designed to reproduce the real world, I realized that unit cell parameters or properties such as temperature-induced phase transition were not reproduced to the precision we expected. In order to make MD more reliable to complement experiments, I first identified the origin of those discrepancies and second I proposed improved force field parameters. By using the optimized parameters, the structural characteristics of the four cellulose allomorphs were better reproduced. Finally, I used these optimized parameters to provide more reliable estimates of some structural characteristics of cellulosic crystals, such as surface properties and hydrogen bonding patterns together with key mechanical properties.

Submitted by WELLINGTON PINE OMORI null (wpomori@hotmail.com) on 2018-03-02T14:43:37Z No. of bitstreams: 1 Tese_Wellington_Pine_Omori.pdf: 3601697 bytes, checksum: 300108bd7832f7e80a842293e639462a (MD5) / Approved for entry into archive by Alexandra Maria Donadon Lusser Segali null (alexmar@fcav.unesp.br) on 2018-03-05T18:02:24Z (GMT) No. of bitstreams: 1 omori_wp_dr_jabo.pdf: 3601697 bytes, checksum: 300108bd7832f7e80a842293e639462a (MD5) / Made available in DSpace on 2018-03-05T18:02:24Z (GMT). No. of bitstreams: 1 omori_wp_dr_jabo.pdf: 3601697 bytes, checksum: 300108bd7832f7e80a842293e639462a (MD5) Previous issue date: 2018-02-07 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A torta de filtro apresenta bagaço residual oriundo do processo de extração do caldo de cana-de-açúcar e quando armazenada por longos períodos, se torna um habitat ideal para o desenvolvimento de comunidades microbianas que atuam na desconstrução da lignocelulose. Nossas análises de dados de sequenciamento de DNA metagenômico sugerem que a torta de filtro armazenada por 40 dias possui uma microbiota com características funcionais e ecológicas exclusivas em relação a outros ambientes com elevada disposição de material lignocelulósico. Assim como em ambientes de compostagem, os filos mais abundantes são Actinobacteria, Proteobacteria, Firmicutes e Bacteroidetes. Dentre os principais genes que estes micro-organismos possuem, estão Glicosiltransferases, Carboidrato Esterases e Glicosil Hidrolases, que atuando em conjunto, são passíveis de desconstruírem a lignocelulose e participarem na liberação de açúcares menores, ácidos orgânicos e outros nutrientes. Neste trabalho, identificamos novas enzimas da família AA10 que oxidam a celulose cristalina, demostrando o potencial deste ambiente em possibilitar a adaptação de micro-organismos que expressam enzimas capazes de desestruturar a celulose altamente condensada, possibilitando a liberação de moléculas de glicose. A comunidade microbiana pode acessar nutrientes como Fósforo e Nitrogênio através da despolimerização da biomassa vegetal ou decomposição da microbiota morta. No ciclo biogeoquímico do nitrogênio, a evaporação de amônia é reduzida pela assimilação desta substância pela comunidade microbiana, sendo que a amônia é produzida pela via de amonificação de nitrato e nitrito. Outro ciclo biogeoquímico identificado na torta de filtro foi o do carbono, ocorrendo diminuição da emissão de metano e gás carbônico devido ao uso destas moléculas no metabolismo microbiano. Por apresentar muitas espécies de micro-organismos termofílicos e funções ecológicas similares a compostagens que alcançaram fase termofílica, a torta de filtro armazenada por 40 dias não aparenta conter micro-organismos patogênicos em elevada abundância, o que poderia ser um indício de sua segurança biológica se usado como adubo no solo. No entanto, recomenda-se que novos estudos sejam realizados neste tipo de ambiente agrícola, afim de avaliar como se comportam principalmente os fungos Neosartorya fumigata e Paracoccidioides brasiliensis, os quais são identificados como agentes patogênicos mas que também são encontrados vivendo na natureza como organismos saprofíticos e em interação com alguns mamíferos, sem causar doença. / The filter cake presents residual bagasse from the process of extracting the sugarcane juice and when stored for long periods, it becomes an ideal habitat for the development of microbial communities that act in the deconstruction of lignocellulose. Our analyzes of metagenomic DNA sequencing data suggest that the filter cake stored for 40 days has a microbiota with unique functional and ecological characteristics compared to other environments with high lignocellulosic material. Thus in composting environments, the most abundant phyla are Actinobacteria, Proteobacteria, Firmicutes, and Bacteroidetes. Glycosyltransferases, Carbohydrate Estersases and Glycoside Hydrolases, which act together, are capable of deconstructing lignocellulose and participate in the release of smaller sugars, organic acids and other nutrients. In this work, we identify new enzymes of the AA10 family that oxidize crystalline cellulose, demonstrating the potential of this environment to enable the adaptation of microorganisms that express enzymes capable of destabilizing highly condensed cellulose, allowing the release of glucose molecules. The microbial community can access nutrients such as Phosphorus and Nitrogen through the depolymerization of the plant biomass or decomposition of the dead microbiota. In the biogeochemical cycle of nitrogen, the evaporation of ammonia is reduced by the assimilation of this substance by the microbial community, and ammonia is produced by ammonification of nitrate and nitrite. Another biogeochemical cycle identified in the filter cake was that of carbon, with a decrease in the emission of methane and carbon dioxide due to the use of these molecules in microbial metabolism. Because it contains many species of thermophilic microorganisms and ecological functions similar to composting that reached the thermophilic phase, the filter cake stored for 40 days does not appear to contain pathogenic microorganisms in high abundance, which could be an indication of its biological safety if used as soil fertilizer. However, it is recommended that new studies be carried out in this type of agricultural environment, in order to evaluate the behavior of the fungi Neosartorya fumigata and Paracoccidioides brasiliensis, which are identified as pathogens but are also found living in nature as saprophytic organisms and in interaction with some mammals, without causing disease.

Made available in DSpace on 2016-01-26T18:55:31Z (GMT). No. of bitstreams: 1 MILENA dissertacao_12_08_2011.pdf: 499305 bytes, checksum: 3ca75cd129170949ca78544d58d71285 (MD5) Previous issue date: 2011-06-20 / Wound healing aims to restore the morphological and functional integrity of the skin. This study evaluates by means of clinical and histologic healing process of skin wounds induced experimentally in rats using a film crystalline cellulose Veloderm ®. Thirty-two rats were divided into two groups: control group (CG) wounds treated with a solution of sodium chloride 0.9% and group veloderm (GV) wounds treated with a film of crystalline cellulose and were evaluated for 26 days at different times. Weight loss was observed in animals from both groups in the early stages, and greater weight gain in the final moments of the GV to the animal, the temperature oscillations in the two groups with predominance in some moments of hypothermia, pinkish wound in the two groups across all time points, greater granulation tissue in animals of CG, the presence of little oozing from the wound and feature in GV and more serous exudation in characteristic bloody GC, GC in the presence of pain and pain in the absence of GV and greater contraction of the wound to the GC, but with complete healing in early GV. Thus, we conclude that the crystalline cellulose film Veloderm ® is effective in the treatment of skin wounds in rats, easy to apply and use, promotes protection and lessen the pain by bringing comfort to the patient, enhances visualization and control of the evolution of the injury keeping humidity, as well as a cost-effective. / A cicatrização de feridas visa restabelecer a integridade morfológica e funcional da pele. Este estudo avalia por meio de exame clínico e histológico o processo de cicatrização de feridas cutâneas induzidas experimentalmente em ratos Wistar, utilizando uma película de celulose cristalina denominada Veloderm®. Trinta e dois ratos foram distribuídos em dois grupos: grupo controle (GC) feridas tratadas com solução de cloreto de sódio 0,9% e grupo veloderm (GV) feridas tratadas com a película de celulose cristalina e foram avaliados durante 26 dias em diferentes momentos. Foi observado perda de peso nos animais dos dois grupos nos momentos iniciais, e maior peso nos momentos finais para os animais do GV, oscilações da temperatura nos dois grupos com predominância em alguns momentos de hipotermia, coloração rósea da ferida nos dois grupos ao longo de todos os momentos de avaliação, maior tecido de granulação nos animais do GC, presença de pouca exsudação da ferida e de característica serosa no GV e maior exsudação de característica sanguinolenta no GC, presença de dor no GC e ausência de dor no GV e maior contração da ferida para o GC, porém com cicatrização completa da ferida mais precoce no GV. Desta forma, conclui-se que a película de celulose cristalina Veloderm® é eficaz no tratamento de feridas cutâneas em rato, de fácil aplicação e utilização, promove proteção e diminui a dor trazendo conforto ao paciente, favorece visualização e controle evolutivo da lesão mantendo a umidade, além de um bom custo benefício.

Made available in DSpace on 2016-07-18T17:53:08Z (GMT). No. of bitstreams: 1 MILENA dissertacao_12_08_2011.pdf: 499305 bytes, checksum: 3ca75cd129170949ca78544d58d71285 (MD5) Previous issue date: 2011-06-20 / Wound healing aims to restore the morphological and functional integrity of the skin. This study evaluates by means of clinical and histologic healing process of skin wounds induced experimentally in rats using a film crystalline cellulose Veloderm ®. Thirty-two rats were divided into two groups: control group (CG) wounds treated with a solution of sodium chloride 0.9% and group veloderm (GV) wounds treated with a film of crystalline cellulose and were evaluated for 26 days at different times. Weight loss was observed in animals from both groups in the early stages, and greater weight gain in the final moments of the GV to the animal, the temperature oscillations in the two groups with predominance in some moments of hypothermia, pinkish wound in the two groups across all time points, greater granulation tissue in animals of CG, the presence of little oozing from the wound and feature in GV and more serous exudation in characteristic bloody GC, GC in the presence of pain and pain in the absence of GV and greater contraction of the wound to the GC, but with complete healing in early GV. Thus, we conclude that the crystalline cellulose film Veloderm ® is effective in the treatment of skin wounds in rats, easy to apply and use, promotes protection and lessen the pain by bringing comfort to the patient, enhances visualization and control of the evolution of the injury keeping humidity, as well as a cost-effective. / A cicatrização de feridas visa restabelecer a integridade morfológica e funcional da pele. Este estudo avalia por meio de exame clínico e histológico o processo de cicatrização de feridas cutâneas induzidas experimentalmente em ratos Wistar, utilizando uma película de celulose cristalina denominada Veloderm®. Trinta e dois ratos foram distribuídos em dois grupos: grupo controle (GC) feridas tratadas com solução de cloreto de sódio 0,9% e grupo veloderm (GV) feridas tratadas com a película de celulose cristalina e foram avaliados durante 26 dias em diferentes momentos. Foi observado perda de peso nos animais dos dois grupos nos momentos iniciais, e maior peso nos momentos finais para os animais do GV, oscilações da temperatura nos dois grupos com predominância em alguns momentos de hipotermia, coloração rósea da ferida nos dois grupos ao longo de todos os momentos de avaliação, maior tecido de granulação nos animais do GC, presença de pouca exsudação da ferida e de característica serosa no GV e maior exsudação de característica sanguinolenta no GC, presença de dor no GC e ausência de dor no GV e maior contração da ferida para o GC, porém com cicatrização completa da ferida mais precoce no GV. Desta forma, conclui-se que a película de celulose cristalina Veloderm® é eficaz no tratamento de feridas cutâneas em rato, de fácil aplicação e utilização, promove proteção e diminui a dor trazendo conforto ao paciente, favorece visualização e controle evolutivo da lesão mantendo a umidade, além de um bom custo benefício.

Plants reduce inorganic carbon to synthesize biomass that is comprised of mostly polysaccharides and lignin. Growth is intricately regulated by external cues such as light, temperature, and water availability and internal cues including those generated by the circadian clock. While many aspects of polymer biosynthesis are known, their regulation and distribution within the stem are poorly understood. Plant biomass is perhaps the most abundant organic substance on Earth and can be used as feedstock for energy production. Various grass species are under development as energy crops yet several of their attributes make them challenging research subjects. Brachypodium distachyon has emerged as a grass model for food and energy crop research. I studied rhythmic growth, a phenomenon important to understanding how plant biomass accumulates through time, and vascular system development, which has biofuel feedstock conversion efficiency and yield. Growth rate changes within the course of a day in a sinusoidal fashion with a period of approximately 24 hours, a phenomenon known as rhythmic growth. Light and temperature cycles, and the circadian clock determine growth rate and the timing of rate changes. I examined the influences of these factors on growth patterns in B. distachyon using time-lapse photography. Temperature and, to a lesser extent, light influenced growth rate while the circadian clock had no noticeable effect. The vascular system transports important materials throughout the plant and consists of phloem, which conducts photosynthates, and xylem, which conducts water and nutrients. The cell walls of xylem elements and ground tissue sclerenchyma fibers are comprised of cellulose, hemicelluloses, and lignin. These components are important to alternative energy research since cellulose and hemicellulose can be converted to liquid fuel, but lignin is a significant inhibitor of this process. I investigated vascular development of B. distachyon by applying various histological stains to stems from three key developmental. My results described in detail internal stem anatomy and demonstrated that lignification continues after crystalline cellulose deposition ceases. A better understanding of growth cues and various anatomical and cell wall construction features of B. distachyon will further our understanding of plant biomass accumulation processes.